Process and apparatus for decomposing gaseous metal compounds for the plating of particles



Nov. 30, 1965 P. E. QUENEAU 3,220,875

PROCESS AND APPARATUS FOR DECOMPOSING GASEOUS METAL COMPOUNDS FOR THE FLA-TING OF PARTICLES Filed May 1, 1961 6 Sheets-Sheet l PA gn I Es COATED I I IA! w PARTICLE I PREHEATER I EXHAUST I I I METAI. I CARBONYI. l FORMATION I I l I J I I EXHAUST I VAPORS I I IHI I I I I I I I I I l ROTATING I I COATED PARTICLES I I D I I I I I I I I l I I I I I L I METAL CARBONYL I I vAPORs I I I I SIZING COATED I OPERATION PRODUCT l IEI IF" I I I I I II INvENTOR. PAUL E. QUENEAU G' FIG. I m

ATTORNEY Nov. 30, 1965 P. E. QUENEAU 3,220,875

PROCESS AND APPARATUS FOR DEGOMPOSING GASEOUS METAL COMPOUNDS FOR THE PLATING OF PARTICLES Filed May 1. 1961 6 Sheets-Sheet 2 INVENTOR PAUL E. QUENEAU ATTORNEY N 2' LL Nov- 30. 1965 P. E. QUENEAU 3,220,875

PROCESS AND APPARATUS FOR DECOMPOSING GASEOUS METAL COMPOUNDS FOR THE PLATING OF PARTICLES 6 Sheets-Sheet 3 Filed May 1, 1961 INVENTOR PAUL EQUENEAU BYCE a(%aQQ9V ATTORNEY Nov. 30, 1 6 P. E. QUENEAU 3,220,875

PROCESS AND APPARATUS FOR DECOMPOSING GASEOUS METAL COMPOUNDS FOR THE PLATING OF PARTICLES Filed May 1, 1961 6 Sheets-Sheet 4 INVENTOR PAUL EQUENEAU (ll-(AM ATTORNEY Nov. 30, 1965 P. E. QUENEAU 3,220,875

PROCESS AND APPARATUS FOR DECOMPOSING GASEOUS METAL COMPOUNDS FOR THE PLATING OF PARTICLES Filed May 1, 1961 6 Sheets-Sheet 5 so 0 0 0 0E:

INVENTOR PAUL E. QUENEAU BYQ. am

ATTORNEY FIG.8

Nov. 30, 1965 P. E. QUENEAU PROCESS AND APPARATUS FOR DECOMPOSING GASEOUS METAL COMPOUNDS FOR THE PLATING OF PARTICLES Filed May 1, 1961 6 Sheets-Sheet 6 INVENTOR PAUL E. OUENEAU ATTORNEY United States Patent PROCESS AND APPARATUS FOR DECOMPGSING GASEGUS METAL CGMPOUNDS FOR THE PLAT- ING 0F PARTICLES Paul Etienne Queneau, Fair-field, Conn., assignor to The International Nickel Company, Inc, New York, N.Y.,

a corporation of Delaware Filed May 1, 1961, Ser. No. 106,652 Claims. (Cl. 117100) The present invention relates in general to an apparatus and method for the decomposition of heat-decomposable gaseous metal compounds and, in particular, for the decomposition of metal carbonyls and, more particularly, to a process for the decomposition of metal carbonyls, such as nickel carbonyl, in rotary decomposer and the apparatus therefor.

Heretofore, decomposition of metal carbonyls such as nickel carbonyl to pellets has been accomplished by using vertical, shaft-type decomposers filled with nickel pellets. In the technique used in these standard static decomposers nickel is deposited on the pellet descending through the shaft by the decomposition of nickel carbonyl flowing upwardly around these pellets. Because of understandable heat distribution problems and the indirect system of heat exchange utilized, these vertical decomposers have limited capacities. Thus, large scale production requires the utilization of batteries of such decomposers. In addition, the prior art decomposers are limited with regard to the strength of carbonyl ga which may be fed therein due to inter-pellet adhesion and resultant shaft blockage as carbonyl content in the inlet gas exceeds a threshold concentration. Normally the nickel content in the inlet gas of these decomposers must be maintained at below of the theoretical maximum.

Tlns limitation in turn restricts its productive capacity.

Although attempts were made to overcome the foregoing difliculties, none, as far as I am aware, when carried into practice commercially on an industrial scale, has achieved the success of the hereindescribed novel process and apparatus.

It has now been discovered that by using the novel decomposition techniques of this invention limitations associated with the standard, vertical decomposer may be overcome. Thus, the present invention provides a method and apparatus which allow more etficient decomposition of metal carbonyls and a much greater metal carbonyl decomposition capacity than any heretofore attainable in the art by utilizing greater metal carbonyl flow rates, using stronger carbonyl gas and operating at higher average temperatures than with standard, shaft-type decomposers. By the present novel process heated particles are tumbled in a novel rotating reactor at a fast enough rate so that the angle of repose of the particles being coated is continuously exceeded and yet slow enough so as to substantially avoid attrition of the particles. Metal carbonyl vapors are fed through the turbulent bed of particles to decompose thereon. The gentle, tumbling action in the bed in the reactor is such as to cause continuous relative movement between particles and so avoid sticking therebetween while at the same time providing a bed of particles which are in constant mutual physical contact. Thus, innumerable and continuously changing circuitous routes for passage of carbonyl vapors through the bed of particles and resulting maintenance of carbonyl vapors therein for an optimum period of time are provided. The depth or thickness of the continuously circulating bed of particles is so regulated that substantially all the metal carbonyl vapors are decomposed therein and so that decomposition vapors leaving the bed of particles are substantially completely free from metal carbonyl.

3,220,875 Patented Nov. 30, 1965 Advantageously, the particles are preheated before being charged to the reactor in a heat exchange vessel which is integral with and rotates on a common axis with the reactor and which discharges the heated particles directly into the reactor. blown up through the bed of gently tumbling particles in the vessel to impart sufficient heat thereto before contact with carbonyl vapors. Particles discharged from the reactor may be recycled thereto by utilizing a conveyor spiral and the rotary motion of the vessel itself. This novel technique provides a simple preheater-decomposer combination with efficient, live-bed gas-solid contact in the rotating vessel compared with indirect heat exchange and relatively dead-bed conditions characteristic of the prior art decomposers.

It is an object of the present invention to provide a method for the decomposition of heat-decomposable gaseous metal compounds involving the use of a substan tially horizontal rotating reactor.

Another object of the invention is to provide a method for decomposing metal carbonyls in a turbulent bed decomposer whereby strong carbonyl gases are processed for metal recovery in massive form and a high throughput is attained.

It is a further object of the invention to provide a method by which metal carbonyls and in particular nickel carbonyl, are decomposed on particles of the metal which are being rotated in a substantially horizontal rotating reactor.

Furthermore, it is an object of the present invention to provide a method for decomposing metal carbonyls and recovering the metals therefrom utilizing a simple, integral preheater-decomposer combination with direct livebed heat exchange in the preheater.

The invention further contemplates providing a method for decomposing a metal carbonyl on gently tumbling core particles such as ceramic particles and/or particles of the metal in the carbonyl or another metal.

It is another object of the invention to provide a novel method for decomposing metal carbonyl gases in a wide range of carbonyl concentrations of up to more than 50%.

Still another object of the invention is to provide a novel process by which particles in a Wide range of sizes may 'be produced from metal carbonyls while utilizing efficient heat exchange with metal particles by direct gassolid contact in a turbulent bed.

It is also the purpose of the invention to provide a novel process for producing metal-coated ceramic particles by the decomposition of heat-decomposable gase ous metal compounds thereon, which metal-coated particles may be ideally utilized in the manufacture of cermets.

A further object of the invention is to provide a novel process for producing metal alloys by the simultaneous I decomposition of various metal carbonyls.

The invention also contemplates providing a novel metal carbonyl decomposer in which detrimental eilects resulting from particle agglomeration, inetficient heat exchange and uneven heat and gas distribution are avoided.

It is also an object of the invention to provide a novel apparatus for decomposing strong metal carbonyl gases to form metals therefrom while at the same time obtaining clean oft-gases from the decomposer substantially devoid of metal carbonyl.

Another object of the invention is to provide a novel, simple, integral preheater and metal carbonyl decomposer utilizing direct, live-bed heat exchange.

It is still another object of the invention to provide a novel dynamic, rotating reactor for decomposing heatdecomposable metal compounds which overcomes some of the limitations associated with static, vertical reactors.

Hot carbon monoxide gas is Other objects and advantages .will become apparent from the following description taken in conjunction with the accompanying drawing in which:

FIGURE 1 illustrates a block flow diagram embodying the novel combination of operations in which a metal carbonyl is decomposed on preheated metallic or nonmetallic core particles;

FIGURE 2 is a vertical longitudinal section of a rotary decomposer embodying the present invention;

FIGURE 3 depicts a vertical cross section of the novel decomposer showing typical distribution of the charge during operation of the rotating reactor;

FIGURE 4 depicts the motion of the particles through a cross section of the rotating reactor during its operation;

FIGURE 5 illustrates the end elevation at location 5-5 of the decomposer shown in FIGURE 2 with a section of the bustle pipe cut away to show one of the special leak-proof control valves;

FIGURE 6 illustrates a detailed section of a type of carbonyl vapor inlet control valve which advantageously may be used in conjunction with the novel decomposer;

FIGURE 7 depicts one of the alternate techniques for feeding metal carbonyl vapors to the novel rotary decomposer embodying the present invention;

FIGURE 8 illustrates a vertical longitudinal section of an alternative rotating reactor of large diameter embodying the present invention, containing a multiple series of carbonyl gas inlet ports, and capable of carrying the invention into practice; and

FIGURE 9 depicts a vertical longitudinal section in diagrammatic form of an advantageous embodiment of the present invention in which the particle preheater is built together with the carbonyl reactor with pellets being transported from the carbonyl reactor discharge back to the preheater by the motion of the combination vessel itself.

Generally speaking, the present invention contemplates decomposing metal carbonyl gases in a novel substantially horizontal rotating reactor, an embodiment of which is shown in FIGURE 2 and described hereinafter, containing a charge of particles, such as pellets, shot, grains, agglomerates or powder of the metal in the carbonyl gas or of another metal or of a non-metallic material, e.g., ceramic materials which may or may not be refractory and glass. Referring to FIGURE 1 which depicts a flow diagram of an embodiment of the present process, the decomposer C, which may be substantially horizontal but is preferably tilted at a small angle to facilitate solids discharge, is rotated to cause a gentle cascading action in the charge of particles being coated, the metal carbonyl vapors are fed through cascading particles and the carbonyl gas is decomposed causing metal deposit on these particles. The reactor is rotated at that speed by which the gently tumbling particles are in constant physical contact with each other and yet are in continuous relative movement with each other so that sticking between particles is eliminated and at the same time are tumbling slowly enough so as to substantially avoid grinding between particles. Thus, a live bed in which continuous mixing is occurring is obtained by the present novel method compared to the dead bed and no mixing used in the standard, vertical decomposers. The thickness of the bed of particles in the reactor is controlled, as aforementioned, so that the metal carbonyl vapors, maintained in the bed for an optimum period of time by passage through innumerable and continuously changing circuitous routes in the bed, are substantially all decomposed therein leaving decomposition vapors substantially completely free from metal carbonyl vapors. The temperature of the charge is maintained within the decomposition temperature range of the metal carbonyl vapor but is advantageously held below the temperature at which significant carbon formation occurs due to carbon monoxide breakdown. Advantageously, the core particles A being charged into the decomposer are preheated externally by any suitable means in particle preheater B, but heat may also be transferred to the bed by induction heating or by internal heating means such as by infra-red heaters or resistance heating of pellet load itself. The coated particles D are discharged from the decomposer and may be sized in operation E to obtain one or more product portions F and an undersize portion G which, if desired, may be recharged into the decomposer after the preheating step. Exhaust vapors H from the reactor, composed primarily of carbon monoxide, may be used in operation J for the formation of metal carbonyl vapors which are fed to rotating reactor C as shown in FIGURE 1. Seed material or nuclei to be coated may be provided by charging metallic or non metallic particles into the decomposer.

Advantageously, particle preheater B can. be integrated with rotating reactor C as illustrated in FIGURE 9 and described in detail hereinafter. Thus, the preheater is joined to the reactor and rotates with it on a common axis with heated particles flowing directly from the preheater to the reactor. Particles to be preheated, including seed particles, are charged to the preheater, which is rotating with the reactor, where they are heated with hot carbon monoxide gases which are passed through the bed of tumbling particles. The heated particles then flow or are discharged into the rotating reactor for deposition of metal thereon from decomposing metal carbonyl vapors. Coated particles are discharged from the reactor and are recycled to the preheater with product being drawn from the discharged particles as desired. Transfer from reactor discharge to preheater charge inlet is most advantageously accomplished by using a conveyor spiral, attached around and rotating with the preheater and reactor. Coated particles discharge from the reactor into the conveyor spiral and are transported back to the particle preheater with product particles being drawn from the recycling stream. By this novel technique a simple, integral, preheatendecomposer is provided utilizing economical, direct, live-bed heat exchange as compared with the dead-bed heat exchange used with standard, vertical decomposers.

Referring to FIGURES 3 and 4, which illustrate the novel techniques by which metal carbonyl gases of high concentration may be processed for metal recovery with formation of off-gases containing substantially no metal carbonyl vapors, particles being coated are maintained at a bed depth in the reactor, as shown by line 58a in FIG- URE 3, regulated so that substantially all carbonyl vapors in the gases being treated are decomposed in the bed. As, shown by the cross section of the reactor in FIG- URE 3, the level of the particle charge 59 is determined by the size of discharge opening 20. Thus, the charge of particles being coated is moving through the reactor and overflowing the lip of discharge opening 20. As the particles flow through the reactor from inlet to outlet end, they are at the same time geing gently cascaded by the slow rotation of the reactor. Thus, the motion of charge, shown as 60 in FIGURE 4, follows the path of arrows 62 with each particle following a circular path through the charge and then moving along the surface of the charge into the turbulent heel portion 62a so that there is a continuous presentation of new surface in the charge.

As stated hereinbefore, the depth of bed depicted by 58a in FIGURE 3 (and by 61 in FIGURE 4) must be such as to allow substantially all metal carbonyl gases being fed to the bed to be decomposed before discharging into the free space of the reactor. thickness of bed must be correlated with its temperature and with the concentration of carbonyl inlet gases and with their rate of flow.

The motion of the particles in the charge, as depicted by arrows 62 in FIGURE 4, combined with their motion through the reactor results in continuous and even rotation of particles in the charge as well as continuous mo- Thus, the depth or tion amongst all particles in the bed with respect to each other. This allows continuous and very uniform metal deposition on all particles in the charge and also eliminates elephant growths on particles and inter-particle adhesion. At the same time, there is continuous inter-particle physical contact in the bed which, combined with the continuous mixing action in the bed, provides innumerable circuitous routes for passage of metal carbonyl gas therethrough and eflicient and complete decomposition of carbonyl vapors therein.

To obtain the desired continuous movement of particles with respect to each other throughout the bed, the reactor is rotated at that speed by which the angle of repose of the particles being coated is continuously exceeded while at the same time keeping grinding between pellets to a minimum. Advantageously, rotation of the reactor should be carried out so as to substantially eliminate attrition of the particles.

More particularly, the present process, relating to the treatment of metal carbonyl vapors such as nickel carbonyl vapor in a novel, rotary decomposer, to produce metal or metal-coated particles such as nickel or nickelcoated particles, may be advantageously carried out in the apparatus depicted in FIGURE 2 which illustrates a substantially horizontal rotating reactor, preferably tilted at a small angle to facilitate particle flow through the reactor, which will be described by way of example in conjunction with the treatment of nickel carbonyl. It will be appreciated, however, that other metal carbonyls or other gaseous, heat-decomposable metal compounds or mixtures thereof may be treated. Referring to FIGURE 2, the novel decomposer may be constructed with a mild steel shell or cylinder 11 with no need for any special lining or cooling means since, as described hereinafter, decomposi tion of carbonyl vapors in the reactor charge is substantially complete so that serious problems presented by decomposition of carbonyl vapor on the inner surface of the cylinder 11 are circumvented. The rotating reactor is supported by rolls 12 with riding rings 13 hearing on these rolls and may be rotated by having one or more of the rolls 12 power driven or by other means such as by driving gear 14.

Preheated nickel pellets and seed or nucleating material for nickel pellets, such as nickel powder, nickel grains, nickel shot, or nickel powder agglomerates, are introduced into the decomposer through the stationary charge inlet 15. If producing nickel powder only, the reactor may be loaded with coarse nickel powder alone. Inlet 15 is sealed to the reactor by suitable means such as by a stationary cylindrical box housing 16 shown in FIGURE 2 maintained in sliding contact with the reactor by suitable means such as by leak-proof interlocking seals 17 and 18. The inner face of the seal 17 is fixed to the stationary box housing 16 by means of flange 19 and the outer face of the seal 18 is fixed to and rotates with the reactor driving gear 14. An absolutely leak-proof fit is maintained between seals 17 and 18, advantageously by a suitable tensioning device (not shown) well known to the art.

The particles to be coated, e.g., nickel pellets, are introduced to the charge inlet through suitable gas sealing means (not shown) well known to those skilled in the art. The coated particles are discharged through discharge port 20 which is attached to and rotates with the reactor and which is sealed to prevent gas leakage by suitable means such as the stationary discharge housing 21 which is maintained in sliding contact with the discharge port 20 by suitable means such as leak-proof interlocking seals 22 and 23 which are maintained in tight contact, advantageously by a suitable tensioning device (not shown) well known in the art. Inner seal 22 is attached to stationary housing 21 while outer seal 23 is attached to and rotates with discharge port 20. The charge outlet 24 on the discharge housing 21 is attached to suitable gas sealing means (not shown) well known to those skilled in the art.

v 28 allow no leaking whatsoever of carbonyl vapors.

The nickel carbonyl gas being treated enters the rotating reactor through gas inlets 25, shown in FIGURE 2, connected to and distributed around the periphery of the reactor shell. The gas can be distributed to these inlet ports from a bustle pipe 26, shown in FIGURE 2 and in detail in FIGURE 5, which is attached to and rotates with the reactor. The nickel carbonyl gas is fed from this bustle pipe to each of the gas inlet ports 25 through feeder lines 27. Flow of gas through each feeder line 27 and each inlet port 25 is controlled by means of valves 28 which are biased to the closed position. A type of valve which can be utilized is shown in detail in FIG URE 6 and is described hereinafter. Each valve 28 and each feeder line 27 is also supported by and rotates with the reactor. Gas inlet ports advantageously project beyond the inside of the reactor shell, as shown by projection 29 in FIGURE 2, to reduce to a minimum any possibility that carbonyl vapors might come in contact with the shell. Valves 28 are operated so as to be open only when in position for passing carbonyl gas upwardly through the zone of the reactor containing the charge of the particles being coated. The valves 28 can be so operated by any suitable means such as by using a fixed stationary cam-track 30 in conjunction with lever arms 31 and valve stems 32 attached to valves 23 shown in FIGURE 5. Thus, when lever arms 31 actuating the valve stems 32 move on to cam-track 30, the valves are opened allowing nickel carbonyl gas to flow into the reactor and when lever arms 31 move off cam-track 30, valves 28 are closed. The bustle pipe 26 and valves 28 may, of course, be positioned in any other manner around the reactor which will supply inlet ports 25 with carbonyl vapors.

It is absolutely necessary, of course, that control valves A valve, such as that shown in detail in FIGURE 6, has been found to be satisfactory in feeding carbonyl vapors to the novel decomposer. Carbonyl vapors flow through inlet 33 of the special valve from bustle pipe 26 into chamber 34 and when the valve is open, the vapors flow into chamber 35 and through outlet 36 of the valve into feeder line 27. The valve is biased to the closed position by means of compressed spring 37 which presses down at 38 on the upper portion of metal assembly 39 attached to valve stem 32 and maintains a leak-proof fit of gasket 40 on shoulder 41. Upon actuation of lever arm 31, when moving onto cam-track 30 attached to the reactor, valve stem 32 is moved upwards along with metal assembly 39 attached thereto. Carbonyl vapors then flow from chamber 34 into chamber 35 through outlet 36 into feeder line 27 and into the reactor. Cylindrical guide vane 42 attached to assembly 39 insures proper seating of gasket 40 on shoulder 41. Leakage between valve head 43 and valve stem 32 is prevented by means of the flexible bellows seal 44 which is attached to metal assembly 39 at 45 and is sealed at its upper end against the valve head by gasket 46. Bellows seal 44 contracts and expands as the valve opens and closes. Any type of flow control valve may be utilized, of course, as long as no leakage of carbonyl vapors occurs, such as, for example, piston type cam operated valves.

Although the cyclic operation of control valves 28 has been described in conjunction with cam track 30, operation of these valves is also attained by electrical means. Thus, by using solenoid-type, electrically operated valves the flow of carbonyl into the reactor can be timed as described hereinbefore.

Other techniques for feeding metal carbonyl vapors to the horizontal rotating reactor may be employed as long as leakage of carbonyl vapors, both outside the reactor and into the open portion of the reactor, is prevented and as long as the general path of the carbonyl vapors through the bed of particles being coated is the Same.

Feeding of carbonyl vapors to the reactor can also be accomplished by using a sliding valve technique. The valve consists of two sliding plates as depicted in FIG- URE 7. Metal carbonyl vapors are fed to plate 47 with a curved slot 48 cut therein. Plate 47 is fitted with a suitable gas-tight seal against plate 49. Holes 50 are cut through plate 49, each of which leads into feeder lines and thence to gas inlet ports on the reactor. Plate 49 and feeder lines from holes 50 rotate with the reactor whereas plate 48 and carbonyl feed line attached thereto are stationary. By proper positioning of slot 48, metal carbonyl vapors are led through only those inlet ports 25 on the reactor which are discharging into the load of particles being coated.

During the operation of the decomposer, at any time, carbonyl gas is entering the reactor through an area on its periphery which is covered with the tumbling particles being coated. The most important consideration in feeding of the carbonyl vapors to the reactor is that the vapors are flowing through a thick enough layer of particles and/or pellets being coated at adequately elevated temperature so that substantially all the carbonyl is de composed before contacting the hot walls of or reaching the free space in the reactor. Depth of charge in the reactor is correlated, as described hereinbefore, with its temperature and with the concentration and rate of flow of carbonyl gases entering the reactor. Thus, it is found that a three foot long, four foot diameter reactor with a charge depth of, for example, about 1.7 feet at the carbonyl gas inlet and one circular series of carbonyl inlet valves will produce over 3000 pounds of nickel per day while handling inlet gases containing over 50% gaseous metal carbonyl and even up to as high a concentration of gaseous carbonyl as can be fed to the reactor without formation of liquid carbonyl in the inlet gases. A twenty foot long, 16 foot diameter reactor with a charge depth of, for example, about seven feet and handling similar concentrations of carbonyl gases will produce over 300,000 pounds of nickel per day.

Depth of load in the reactor may be varied by the size of reactor discharge opening and/or by the degree of inclination of the reactor from inlet to outlet end. The larger the load in the reactor, the more inlets on the periphery which can be utilized at one time for discharging metal carbonyl vapors into the layer of material being coated. Capacity of the novel decomposer is increased by approximately the square of the diameter and is further increased by lengthening the reactor and using a multiple series of carbonyl inlet ports located along the reactor around its periphery. FIGURE 8 illustrates such a reactor of larger diameter and greater length with a multiple series of carbonyl inlet ports 63 depicted in the figure. Doubling the length of the reactor is found to approximately double the capacity of the decomposer.

It has been found highly advantageous in the operation of the decomposer to maintain the longtiudinal axis of the reactor inclined at a small angle to the horizontal with the charge outlet end lower than the charge inlet end. This facilitates flow of material through and discharge of material out of the reactor and also permits slower reactor rotational speeds. Increasing the inclination of the reactor means faster passage therethrough and a higher circulating load, i.e., material remains a shorter length of time in the decomposer between heating stages.

Referring again to FIGURE 2, nickel carbonyl gas is fed through stationary gas inlet pipe 51 via pipe connection 52 into bustle pipe 26. Pipe connection 52 rotates with the reactor and is sealed at its connection with inlet pipe 51 by sealing rings 53 and 54. Spent gas is exhausted by suitable means such as through gas outlet 55 on charge inlet 15, shown in FIGURE 2. Care must be taken that inlet ports 25 and, in particular, projections 29 of these ports, which are in close proximity to hot pellets or other particles in the decomposer,

do not become hot enough to allow decomposition of carbonyl vapors and plating of metal therein. These inlet ports can be cooled such as by maintaining a spray of cooling water thereon. Splash guards 56 channel the water and keep it flowing around the periphery of the reactor where inlet ports 25 are located. Cooling of inlet connection 52, which is also in close proximity to hot charge exiting from the reactor, must be maintained either by water jacketing or splash techniques. A simple technique, such as that shown in FIGURE 2, can be utilized for this cooling. Line 52 is surrounded by pipe 57 (also shown in FIGURE 5) which ends in a scoop arrangement 58. As the reactor turns, scoop 58 passes into a trough of cooling water scooping up water which runs back into pipe 57 and cools line 52. As the reactor turns farther, the water runs back out and is replenished by the next pass of the scoop. Cooling of the reactor shell, charge inlet 15 and exhaust gas outlet 55 is unnecessary during the operation of the novel decomposer since decomposition of carbonyl vapors with in the charge is substantially complete so that contact of walls of the reactor and gas outlet lines with undecomposed carbonyl vapors with resulting plating out of metal, a problem plaguing standard powder and pellet decomposers, has been substantially eliminated by the hereindescribed novel techniques.

In treating nickel carbonyl vapor according to the present invention, and utilizing the novel decomposer hereindescribed, nickel metal particles, such as nickel pellets, nickel shot, crushed nickel, nickel powder agglomerates and coarse nickel powder, are utilized as nuclei or seed material on which to plate the nickel metal. Because of the great degree of flexibility of the present novel process, nickel metal particles of a wide size range may be produced. Thus, variable sized particles from powder up to one inch diameter balls can be obtained, the size of the particle being controlled by carbonyl concentration, solids temperature and residence time in the decomposer.

Size of seed particles utilized in the reactor is controlled mostly by velocity and volume of inlet and exhaust gases. Thus, particles cannot be utilized which will be substantially all blown out of the reactor.

The particles being coated are preheated, to provide the heat for decomposing the nickel carbonyl vapor fed into the decomposer, to above about 350 F. and advantageously at least about 400 F. by any suitable means. The pellets should advantageously be preheated to a temperature such that they are not above about 550 F. in the reactor although higher temperatures may be employed as long as carbon formation in the reactor is substantially avoided. In any case, the nickel particles are heated to as high a temperature as practical while avoiding the formation of carbon. It is to be understood, of course, that addition agents, such as ammonia, for reduction of carbon deposition may be utilized. For optimum decomposition of the nickel carbonyl entering the reactor, the particles leaving the cylinder should be at a temperature of at least about 300 F. Electric induction or electric resistance heating or indirect heat exchange may be utilized, but preferably the particles are heated by direct contact with hot gas, advantageously with hot carbon monoxide. Carbon monoxide used for preheating can be recirculated over and over through this system.

It can be appreciated, then, that a wide latitude of heat exchange apparatus can be utilized for preheating solids being fed to the decomposer. Thus, a two-stage rotating reactor technique can be utilized, using the first reactor for preheating and the second for decomposition. Preheating of circulating particles can also be accomplished using fluid bed techniques with hot inert gases or hot carbon monoxide as the fluidizing medium. Preheating of particles being coated can be accomplished directly in the decomposition reactor. Thus, hot carbon monoxide is blown into the particle charge at locations remote from metal carbonyl vapor inlets to preheat it. The preheated particles then move into the area of the reactor through which metal carbonyl gases are being directed as described hereinbefore. By this technique, necessary provision of separate preheating means is eliminated.

Advantageously the particle preheater vessel and the carbonyl reactor vessel are built together with the two vessels rotating around a common axis as illustrated by the vertical longitudinal section of the joined vessel shown in diagrammatic form in FIGURE 9. As shown on this figure, particles overflowing from the carbonyl reactor vessel are advantageously transported by means of a conveyor spiral and the motion of the joined vessels themselves to a feed hopper and screen with product particles being screened out and unfinished particles being charged into the preheater vessel.

Referring to FIGURE 9, particle preheater vessel 64 and carbonyl reactor vessel 65, which are joined by neck 66, are supported on rolls 67 with riding rings or tires 68 hearing on these rolls and are rotated by having one or more of the rolls 67 power driven or by other means such as by driving gear 69 turning ring gear 79. Operation of the apparatus depicted in FIGURE 9 will be described by way of example in conjunction with the treatment of nickel carbonyl. It will be appreciated, however, that other metal carbonyls or other gaseous, heatdecomposable metal compounds or mixtures thereof may be treated. Nickel pellets and seed material for nickel pellets, such as nickel shot, nickel powder or nickel powder agglomerates, are introduced into preheater vessel 64- through charge inlet 71. The pellet charge in preheater 64 is being subjected to a gentle cascading action by the slow rotation of the vessel. Hot carbon monoxide gases are led into the preheater through gas inlets 72 which are fed by feeder lines 73 and inlet line 74. By suitable control means, such as that described hereinbefore in conjunction with FIGURES 2 and 5, the hot carbon monoxide gases are passed upwardly through the cascading particles to preheat them. The spent carbon monoxide gases are then vented from the preheater vessel such as through gas outlet 75.

Preheated pellets from preheater 64 overflow into carbonyl reactor vessel 65 through neck 66 or advantageously are discharged into neck 66 and thence into reactor 65 by scoop means 76 which carry pellets up from the bottom of preheater 64. Preheated pellets in reactor 65 are maintained in a gentle cascading motion as described hereinbefore and nickel carbonyl vapors are directed through inlet line 77, feeder lines 78 and gas inlets 79 into the reactor. By suitable means, as described hereinbefore, the flow of carbonyl vapors is controlled so that the vapors are always passing upwardly through the pellet charge. Gases of decomposition are exhausted from reactor 65 through gas outlet 80. Preferably, the preheater and reactor combination is tilted at a small angle, the reactor being lower, to facilitate the flow of pellets through the two vessels. Pellets flow from reactor 65 into discharge housing 81 and then into conveyor spiral 82. By the motion of the vessels and by means of a sand wheel type of discharge, well known to those skilled in the art, the pellets are lifted in the conveyor spiral into feed hopper 83. The outlet end of the spiral is provided with a double airlock 84 which is controlled to discharge only when its outlet is above feed hopper S3. Seed particles may advantageously be added through charge port 85 at this point in the system.

Pellets leaving airlock 84 are passed over screen 86 with product pellets being discharged through outlet port 87 and undersize pellets falling through and into hopper 88. From hopper 88 the recirculated particles and added seed particles are discharged into preheater vessel 64 through airlock 89 and line 9%. Carbonyl inlet line 77 and gas inlets 7 9 are water cooled, if desired, by suitable id means such as those described in connection with FIG- URE 2 hereinbefore. Suitable gas seals, well known to those skilled in the art, are provided in carbon monoxide inlet line 74 and nickel carbonyl inlet line 77 (shown by 91 and 92, respectively, in FIGURE 9) and on the preheater inlet end and reactor outlet end (shown by 93 and 94, respectively, in FIGURE 9).

This hereindescribed embodiment of the invention illustrated by FIGURE 9, thus provides a simple, integral preheater-decomposer system for treating metal carbonyls providing eificient and effective preheating utilizing direct, live-bed heat exchange as compared with dead-bed heat exchange in standard decomposers and eliminating separately powered and controlled pellet recycling and preheating means.

Adaquate heat of decomposition can be supplied to the reactor by preheating of the pellets or other particles, but this heat can be supplemented or replaced by using internal heaters in the reactor, such as infra-red heaters which do not rotate with the reactor but are fixed through suitable seals to the external stationary part of the apparatus. Plating of nickel on such heaters is avoided because of their own high temperature and because of the substantially complete decomposition of carbonyl vapor before it escapes the solid charge in the decomposer. Utilization of infra-red heaters in the reactor has a beneficial effect in that the upper surface of the bed of particles being coated is heated to the highest temperature insuring that no metal carbonyl vapors escape from the bed without being decomposed. Heating of the reactor charge may also be accomplished by electrical heating such as by electrical resistance heating or, alternatively, induction heating.

Although conveyance of circulating particles from the reactor discharge to metal particle preheater can be accomplished by means such as by bucket elevator or advantageously pneumatically, e.g., using hot carbon monoxide as the elevating means, it is advantageous to utilize the motion of the reactor itself for transfer of circulating particles to the preheating step, particularly when another reactor is being utilized for preheating or when preheating by hot carbon monoxide is occurring in the decomposition reactor itself and this is accomplished by means such as that illustrated and described hereinbefore in connection with FIGURE 9.

The reactor is advantageously rotated at that minimum speed which insures a gentle, tumbling action resulting in continuous rotation of each particle and in continuous movement of all particles in the charge with respect to each other throughout the reactor. Rotation is kept fast enough to prevent any inter-particle adhesion or uneven pellet growth. Carbonyl vapors, then, are passing up through a dynamic, live bed of particles with continuous mixing in the bed and at the same time constant physical contact throughout the bed. Thus, uneven heat distribution, channelling and irregular metal deposition which occurs in the static, dead bed of the decomposers used in the prior art is eliminated in the present novel decomposer. The reactor is rotated at a fast enough rate so that the angle of repose of the particles being coated is continuously exceeded. It is found, for example, that in producing half to three quarter inch diameter nickel pellets by the present invention, to attain the desirable bed tumbling action an angle of about 25 (the angle of repose of the cascading pellets) of the bed surface in the reactor must be continuously exceeded. It is to be noted that the angle of repose of a stationary pile of the same pellets approaches 30. Rotation of the reactor at speeds higher than that which causes adequate bed turbulence will, of course, result in greater power consumption and may also result in possible undesirable grinding action amongst the particles. Speed of rotation of the reactor is controlled to keep particle attrition to a minimum and in any case so that not more than about one tenth as much metal is being ground from as is being deposited on particles being coated. The speed of the reactor is of a different order of magnitude compared to that of the comminution ball mill employed for grinding in the mineral industry, being less than of the normal operating speed of such a mill of comparable diameter and preferably closer to about 1% of said speed. Thus, a reactor with an inside diameter of 4 feet and a length of 3 feet has been employed effectively at speeds of as low as about 0.1 rpm. in practicing the hereindescribed invention to form nickel pellets.

As aforementioned in the description of the novel decomposer, nickel carbonyl gas from a carbonyl volatilizer or other source enters around the periphery of the reactor through inlet ports 25, shown in FIGURE 2, which are timed to open when carbonyl gas will be blown up through the charge to decompose on the nickel pellets as has been previously explained and described. Very strong nickel carbonyl gas may be blown into the reactor without causing sticking of the charge and irregular growths and agglomeration of pellets are avoided because of the excellent continuous positive movement of the balls with regard to each other and because of superior heat exchange throughout the charge. Sticking and irregular growths are avoided also because of the uniformity of temperature and because of the very even gas distribution throughout the solids mass. The allows much higher carbonyl throughput than with decomposers heretofore used in the art. Thus, it has been found that gases with a nickel content in the order of more than 1500 grams per cubic meter may be treated compared to less than about 300 grams per cubic meter in prior art decomposers. Because of the flexibility of the hereindescribed novel decomposer, gases with a low nickel content in the order of 100 grams per cubic meter may readily be treated if desired. The carbonyl vapor is fed in with an inert gas such as carbon monoxide, nitrogen or carbon dioxide although use of carbon monoxide eliminates problems arising relating to the necessity for separating gases after decomposition is complete.

Normally, the carbonyl gas entering the decomposer through gas inlet pipe 51, shown in FIGURE 2, is maintained at about atmospheric pressure but elevated pressures, e.g., 1000 pounds per square inch, may be utilized. Preheating of carbonyl vapor entering the decomposer increases the tendency for decomposition of metal carbonyl in inlet lines which would result in metal buildup in the lines and eventual plugging difiiculties. Use of carbonyl vapor cooled below atmospheric temperature is not precluded from the process but since the carbonyl decomposition reaction is endothermic such cooling would result in heavier heat requirements in the reactor. In any case, the lower temperature limit is the vapor pressure of the nickel carbonyl fed to the reactor. The carbonyl vapor advantageously is introduced at that maximum temperature wherein metal is not deposited in the lines. As described hereinbefore, it is advantageous to water or air cool the inlet ports and feed line 52 to insure that nickel carbonyl does not decompose in the inlet lines.

Decomposition of carbonyl vapor in the novel decomposer proceeds at a highly efi'icient rate so that the exit vapors leaving through gas outlet port 55 can readily contain less than 0.1% of the original nickel carbonyl entering the reactor. The decomposition efiiciency of the present novel, dynamic rotating decomposer, then, can be at least about 99.9%. Thus, less than of one percent of the nickel carbonyl vapors entering the present novel reactor leave undecomposed Whereas in standard decomposers used in the prior art more than one percent of nickel carbonyl vapors entering the reactor leave undecomposed. In treating nickel carbonyl gas with a nickel content of 200 grams per cubic meter in the present novel decomposer an exit gas containing nickel in the order of 0.2 gram per cubic meter or less is obtained. To show the decomposition efiiciency which can be attained in the present novel process and apparatus, a reactor operating with nickel carbonyl inlet gases containing over 1200 grams per cubic meter of nickel produced exit gases containing only about 0.16 gram per cubic meter of nickel. This very high decomposition efiiciency is extremely important since it eliminates plating problems and possible difiiculties in compressing recycle gas which cause signifcant maintenance costs.

The decomposer is advantageously operated at atmospheric pressure to minimize both air leakage into and carbonyl vapor leakage out of the system. Operation of the decomposer at slightly below atmospheric pressure will prevent the possibility of leakage of the highly noxious carbonyl vapors. The decomposer, as aforementioned, may be operated at pressures considerably above atmospheric but decomposition efiiciency is affected and danger of carbonyl leakage is considerably increased.

Coated nickel particles are discharged through discharge port 20 and discharge housing 21 shown in FIG- URE 2. This discharging can be continuous in nature. The particles can "be classified into two fractions, one being a product fraction containing only particles larger than that minimum size desired and an undersize fraction which is returned to the preheater before being charged back into the decomposer. In recycling undersize material through the preheater, if no internal heat ing is used in the reactor, it is necessary to provide enough heat by this recirculation to account for heat losses from the reactor and lines to and from the reactor as Well as the heat required to decompose the metal carbonyl. In such a case the product fraction consists of a minor portion of the particles discharged from the reactor while the recycled fraction consists of a major portion of the material discharge. Typical circulation loads of about 10 tons per hour for a pound per hour production unit to about 5 tons per 100 pounds of nickel produced in a 5 tons per hour production unit are found to be necessary. This recirculation of particles through the preheater can, of course, be reduced or even eliminated by any preheating in the reactor itself or by supplementary heating supplied either internally or through the reactor walls.

As aforementioned, capacity of the decomposer is increased approximately in the order of the square of the diameter and directly as the length of the reactor. Thus, the aforementioned over one ton per day production unit has a reactor diameter of 4 feet and a length of three feet whereas a production unit of over 100 tons per day (one hundred times the capacity) has a reactor diameter and length of approximately 16 feet and 20 feet, respectively. It is obvious to those skilled in the art that the present novel carbonyl reactor occupies considerably less volume than standard decomposers of the prior art with equal capacity.

Although operation of the decomposer on a continuous basis is most advantageous, it is, of course, possible to operate it on a batch basis by loading the reactor with seed particles and gradually building up these particles to the size desired without adding further seed particles. Upon reaching the desired size the particles are discharged as product and a new batch of seed particles is then charged to the reactor. Recirculation of pellets within the system without drawing 01f product is carried out to supply the necessary heat with supplementary heat supplied internally if necessary.

The product of nickel particles obtained from the decomposer, which may consist of coarse nickel powder or larger particles of up to one inch diameter or bigger nickel pellets, is found to be uniformly dense throughout with no sticking between particles, irregular growths or agglomeration of particles. Very uniform nickel pellets can be obtained by the hereindescribed novel process which are excellent for use in special steel making or high temperature alloy making or for any other application requiring high purity nickel metal.

For the purpose of giving those skilled in the art a better understanding of the invention, the results of three continuous-run tests on the decomposition of nickel carbonyl vapor in a rotary decomposer similar to that shown and described hereinbefore are outlined in Table I. The reactor utilized for these runs had an inside diameter of 4 feet and a length of 3 feet. The nickel product from these test runs was in the form of dense, uniformly sized and relatively smooth-surfaced half-inch diameter pellets. Seed material for the formation of these pellets consisted of fine nickel shot. Nickel feed and production rate for these tests varied between about 40 pounds and about 50 pounds of nickel per hour.

The results of three more test runs in the same apparatus as used in the runs of Table I are shown in Table II. Feed material and product for these runs was the same as those shown in Table I except that in these three runs nickel feed and production rate varied between about 80 pounds and about 125 pounds of nickel per hour.

Table II i Run D Run E Run F Feed, pounds of Nickel per hour 83 102 126 Feed, grams of Nickel per cubic meter" 820 975 1, 160 Feed, volume, cubic feet per minute." 27 28 29 Exit Gas, grams of Nickel per cu. meter 0. 44 0. 44 0. 16 Exit Gas, volume, cubic feet per minute. 59 65 74 Decomposition Efiiciency, percent 99. 90 99. 91 99. 97 Temps. F., Pellets into Decomposer 465-470 455-462 452 Temps. F., Pellets out of Decomposer- 395-400 380-390 370 It is to be seen that the present invention provides a novel process and apparatus for decomposing heat-decomposable metal compounds to form metals therefrom which allows much higher metal carbonyl throughput and which treats metal carbonyl vapors of much higher concentration than that attainable with standard decomposers known to the prior art. Thus, the capacity of the present novel reactor is much higher than that of standard decomposers while occupying a much smaller volume. At the same time, the decomposition efiiciency attained by the present novel process is much improved over that of the prior art decomposers with the result that exhaust gases with lower carbonyl contents are obtained greatly reducing or eliminating problems associated with metal plating on apparatus and with compression of recycle gas.

It is to be noted that although the present invention has been described in conjunction with a substantially horizontal tumbling cylinder, other means for causing continuous interparticle motion can be utilized in which carbonyl vapors can be decomposed efiiciently at a high rate as long as the same general path of the carbonyl vapors through the bed of tumbling particles as described hereinbefore is attained.

Although the present invention is particularly applicable to the decomposition of nickel carbonyl in the novel decomposer hereindescribed, it can also be applied to the decomposition of other metal carbonyls such as iron carbonyl, cobalt carbonyl, chromium carbonyl, molybdenum carbonyl and tungsten carbonyl or mixtures of metal carbonyls, Iron, cobalt, chromium, molybdenum, tungsten or other metal particles can be used instead of 14 nickel particles in the novel reactor with Vapors of the carbonyl of the appropriate metal being introduced for decomposition on the metal particles. When treating other metal carbonyls, it is necessary, of course, to control the temperature of the recirculating particles so that they are above the decomposition temperature of the particular carbonyl being treated and yet below the temperature at which carbon formation begins. Temperature of carbonyl inlet gases also must be maintained below the decomposition temperature of the particular carbonyl being treated to prevent plating of metal on inlet lines.

Furthermore, the invention provides a method for coating non-metallic refractory or ceramic materials, e.g., metal carbide particles or particles of ceramic materials such as aluminum oxide, magnesium oxide, titanium oxide, zirconium oxide and thorium oxide, with a layer of metal such as nickel by charging seed particles such as powder or grains of the ceramic or metal carbide or other non-metallic material into the novel rotary decomposer of this invention and decomposing a particular metal carbonyl on the particles to form metal coated non-metallic particles. By utilizing a series of the novel decomposers, non-metallic particles can be coated with first a layer of one metal and then with layers of other metals. Thus, for example, non-metallic particles can be coated with layers of nickel, iron, cobalt, chromium, molybdenum and tungsten metals by injecting the carbonyls of these metals into separate decomposers in series. Non-metallic particles can also be coated simultaneously with a number of metals by feeding more than one metal carbonyl to the reactor at the same time. The metalcoated ceramic, refractory or other non-metallic particles can then be subjected to heat treatment for diffusion, annealing, dispersion hardening and other purposes. Ceramic particles coated by the present novel process advantageously may be pressed, sintered and/or heat treated to form cermet materials and non-metal-containing dispersion hardening alloys. The hereindescribed novel metal coating techniques may also be utilized in producing supported metal catalyst materials.

It is to be noted that the novel decomposer can be utilized to concurrently coat non-metallic particles and metallic nickel pellets by charging, for example, only preheated nickel pellets larger than the non-metallic particles being charged into the reactor and classifying the nickel pellets and nickel-coated non-metallic particles being discharged from the reactor. It is also to be observed that vari-sized metal particles can be produced in the novel decomposer concurrently by feeding different sized seed particles into the reactor, decomposing the desired metal carbonyl onto the particles and separating fractions of the desired sizes of metal particles from the reactor discharge.

It is to be noted also that metal particles can be coated with other metals by the invention, e.g., iron particles can be coated with nickel by the decomposition of nickel carbonyl in the novel decomposer. Also, metallic particles can be coated with more than one metal simultaneously in the novel decomposer by injecting more than one metal carbonyl, e.g., nickel, iron and cobalt carbonyls, and decomposing the carbonyls at the same time. This last-mentioned technique provides a novel means for producing metal alloys from mixtures of metal carbonyls. Desirable alloys can be formed by feeding the correct ratios of metal carbonyls to the novel decomposer. The alloy particles may then be subjected to heat treatment for diffusion, annealing and other purposes.

It is to be further noted that, although the present invention is described in conjunction with metal carbonyls, other heat decomposable, gaseous, metallic and non-metallic compounds may be fed to the hereindescribed novel decomposer to provide particles with any type of coating from the decomposition of these gases in the reactor. Other heat decomposable metallic compounds which may be fed to the reactor in the gaseous state include cobalt nitrosyl carbonyl, tin hydride, antimony hydride, beryllium iodide and nickel iodide.

Although the present invention has been described in conjunction with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the invention and appended claims.

I claim:

1. A method for decomposing a metal carbonyl vapor to form the metal of said carbonyl which comprises heating core particles in hot carbon monoxide gas to above the decomposition temperature of said metal carbonyl but below the temperature at which carbon formation will occur during the decomposition of said metal carbonyl to provide heat for decomposition of said metal carbonyl, gently tumbling said core particles in a decomposition zone at that rate at which attrition of the particles being tumbled is substantially avoided but at which continuous non-suspended relative movement between particles is induced and particle agglomeration is prevented, feeding vapor of said metal carbonyl at below its decomposition temperature through said tumbling core particles maintained in a depth of bed regulated such that substantially all said metal carbonyl decomposes on and coats said core particles with the metal in said carbonyl, removing gases of decomposition substantially completely free from metal carbonyl vapors and withdrawing said metal-coated core particles from said decomposition zone.

2. A method for decomposing nickel carbonyl vapor to form nickel metal therefrom which comprises heating core particles of nickel metal in hot carbon monoxide gas to between about 350 F. and about 550 F. to provide heat for decomposition of said nickel carbonyl, gently tumbling said core particles in a decomposition zone at that rate at which attrition of the particles being tumbled is substantially avoided but at which continuous non-suspended relative movement between particles is induced and particle agglomeration is prevented, feeding vapor of said nickel carbonyl at below its decomposition temperature through said tumbling core particles to substantially completely decompose on and coat said core particles with the nickel in said carbonyl, removing gases of decomposition substantially completely free from nickel carbonyl vapors and withdrawing said nickel-coated core particles from said decomposition zone.

3. A process for decomposing at least one metal carbonyl and coating particles with metals therefrom which comprises feeding said metal carbonyls into a decomposition zone containing heated, non-suspended, gently tumbling particles, directing said metal carbonyls through said gently tumbling particles to substantially completely decompose on and coat said particles w'th the metals in said carbonyls, removing gases of decomposition substantially completely free from metal carbonyl vapors and withdrawing metal-coated particles from said decomposition zone.

4. A method for decomposing a metal carbonyl which comprises establishing a decomposing zone containing a bed of heated solid particles having a controlled depth and a heating zone containing a bed of solid particles, inducing motion within said bed of heated particles-in said decomposing zone such that non-suspended interparticle movement is created and interparticle contact is maintained but substantial attrition of said particles is avoided, supplying hot gas to said bed of solid particles in said heating zone to heat said bed of solid particles to a temperature in excess of the decomposition temperature of said metal carbonyl, transferring heated particles from said heating zone to said decomposing zone, flowing a gas stream containing vapor of said metal carbonyl to be decomposed substantially upwardly through said bed of heated solid particles in said decomposing zone at a rate correlated with respect to said controlled depth of said bed to effect substantially complete decomposition of said metal carbonyl upon said particles, and transferring solid particles from said decomposing zone to said heating zone while withdrawing a finished solid product therefrom.

5. A method according to claim 4 wherein the metal carbonyl to be decomposed in selected from the group consisting of nickel carbonyl, iron carbonyl, cobalt carbonyl, chromium carbonyl, molybdenum carbonyl and tungsten carbonyl.

6. A method for decomposing a metal carbonyl which comprises establishing a bed of solid particles having a controlled depth, heating said bed to a temperature above the decomposition temperature of said metal carbonyl to be decomposed, inducing motion within said bed such that non-suspended, gently tumbling, interparticle movement is created and interparticle contact is maintained but substantial attrition of said particles is avoided, flowing a gas stream containing said metal carbonyl vapor to be decomposed substantially upwardly into said bed, controlling the rate of introduction of said stream of metal carbonyl with respect to said controlled depth of said bed to etfect substantially complete decomposition of said metal carbonyl within said bed, and withdrawing above said bed gaseous products of said decomposition substantially devoid of said metal carbonyl.

7. A method for decomposing nickel carbonyl which comprises establishing a bed of solid nickel particles having a controlled depth, heating said bed to a temperature above the decomposition temperature of nickel carbonyl, inducing motion within said bed such that non-suspended, gently tumbling, interparticle movement is created and interparticle contact is maintained but substantial attrition of said nickel particles is avoided, flowing a gas stream containing nickel carbonyl vapor to be decomposed substantially upwardly into said bed, controlling the rate of introduction of said stream of nickel carbonyl with respect to said controlled depth of said bed to effect substantially complete decomposition of said nickel carbonyl Within said bed to coat and cause growth of said particles, and withdrawing above said bed gaseous products of said decomposition substantially devoid of nickel carbonyl.

8. A method for decomposing nickel carbonyl which comprises establishing a bed of heated nickel particles having a controlled depth in contact with a surface, moving said surface at a slow rate while maintaining said contact to impart to said particles in said bed a gently tumbling motion wherein interparticle movement is created and interparticle contact is maintained but substantial attrition of said nickel particles is avoided, flowing a gas stream containing nickel carbonyl to be decomposed substantially upwardly through the base of said bed at a rate insutficient to cause suspension of said particles in said bed, controlling the rate of introduction of said stream of nickel carbonyl With respect to said controlled depth of said bed to effect substantially complete decomposition of said nickel carbonyl upon said heated nickel particles and to cause growth of said particles and cooling of said particles due to the decomposi tion reaction, heating nickel particles to a temperature exceeding the decomposition temperature of nickel carbonyl in a heating zone, circulating heated nickel particles from said heating zone to said bed to supply reaction heat to said bed and circulating cooled nickel particles from said bed to said heating zone while Withdrawing a finished solid product therefrom.

9. An apparatus for decomposing heat-decomposable metal vapors and forming metals therefrom which comprises a rotating reactor having a rotatable, cylindrical shell, a gas-sealed solids charge port and a leak-proof exhaust gas outlet located substantially on the longitudinal axis at one end thereof, a gas-sealed solids discharge port located substantially on the longitudinal axis at the other end thereof, said shell having leak-proof gas inlets fixed thereto, insert into and projecting beyond the inner curved surface of said shell and spaced substantially equally around the periphery of said rotatable shell, said gas inlets each having gas inlet lines attached thereto and rotatable with said shell, leak-proof flow control means in each of said gas inlet lines with actuating levers attached thereto, stationary curved track means located in the lower portion of travel of said shell and positioned to intercept said actuating levers on each of said flow control means, gas feeding means connected to each of said gas inlet lines and rotatable with said shell, a gas feed line attached to said gas feeding means and rotatable with said shell, a fixed gas feed pipe located on the longitudinal axis and at the solids discharge port end of said reactor leading to said gas feed line and joined to said gas feed line with a leak-proof seal, a solids discharge housing attached to said solids discharge port with a gas-tight seal, solids circulating means and product removal means attached to said solids discharge housing, said solids circulating means attached to and discharging into solids preheating means, solids transfer means connecting the discharge end of said solids preheating means With said solids inlet port on said rotating reactor, supporting means for said reactor and means for rotating said reactor about the longitudinal axis thereof.

10. A reactor for decomposing heat-decomposable metal vapors comprising a rotatable shell having a gassealed solids charge port at one end thereof, a gas-sealed solids discharge port at the other end thereof, supporting means for said reactor, means for rotating said shell about a central longitudinal axis, leak-proof gas inlets attached to said rotatable shell around the periphery thereof, cooling means for cooling said gas inlets, gas-inlet lines leading to each of said gas inlets on said shell attached to and rotatable with said shell, leak-proof flow control means connected into said gas-inlet lines adjusted to allow gas flow through said gas-inlet lines and said gas inlets at any time only into the lower portion of said rotatable shell,

leak-proof gas feeding means connected to said flow control means, a leak-proof exhaust gas outlet attached to said reactor and heating means located within said reactor to direct heat downwardly upon a solids charge contained within said rector.

References Cited by the Examiner UNITED STATES PATENTS 1,973,703 9/1934 Goucher et al 117-46 2,161,950 6/1939 Christensen 11746 2,702,523 2/1955 Prestwood et al 118-48 2,792,438 5/1957 Dunn 11848 2,888,375 5/1959 Drummond 117-107 2,948,918 8/1960 Austin 264-1 17 2,986,457 5/1961 Jones 26624 3,068,091 12/1962 Kirkland 266-24 FOREIGN PATENTS 1,032,550 6/1958 Germany. 1,086,106 7/ 1960 Germany.

JOSEPH B. SPENCER, Primary Examiner.

RICHARD D. NEVIUS, Examiner 

1. A METHOD FOR DECOMPOSING A METAL CARBONYL VAPOR TO FORM THE METAL OF SAID CARBOXYL WHICH COMPRISES HEATING CORE PARTICLES IN HOT CARBON MONOXIDE GAS TO ABOVE THE DECOMPOSITION TEMPERATURE OF SAID METAL CARBONYL BUT BELOW THE TEMPERATURE AT WHICH CARBON FORMATION WILL OCCUR DURING THE DECOMPOSITION OF SAID METAL CARBONYL TO PROVIDE HEAT FOR DECOMPOSITION OF SAID METAL CARBONYL, GENTLY TUMBLING SAID CORE PARTICLES IN A DECOMPOSITION ZONE AT THAT RATE AT WHICH ATTRITION OF THE PARTICLES BEING TUMBLED IS SUBSTANTIALLY AVOIDED BUT AT WHICH CONTINUOUS NON-SUSPENDED RELATIVE MOVEMENT BETWEEN PARICLES IS INDUCED AND PARTICLE AGGLOMERATION IS PREVENTED, FEEDING VAPOR OF SAID METAL CARBONYL AT BELOW ITS DECOMPOSITION TEMPERATURE THROUGH SAID TUMBLING CORE PARTICLES MAINTAINED IN A DEPTH OF BED REGULATED SUCH THAT SUBSTANTIALLY ALL SAID METAL CARBONYL DECOMPOSES ON AND COATS SAID CORE PARTICLES WITH THE METAL IN SAID CARBONYL, REMOVING GASES OF DECOMPOSITION SUBSTANTIALLY COMPLETELY FREE FROM METAL CARBONYL VAPORS AND WITHDRAWING SAID METAL-COATED CORE PARTICLES FROM SAID DECOMPOSITION ZONE. 